Hardware manual

Microcomputer Technical Q&A
50
Q&A No.: QAH8S-042
Category: Bus Controller
Subject: Bus Release Wait Time after BREQ Input
Question
In what circumstances is there a long wait time from BREQ input to BACK output?
Answer
A BREQ request is held pending in the following cases:
• In DMAC data transfer in burst mode or block transfer mode
• In DTC data transfer
• When a wait is inserted in an external address access
Applicable Products
Applicability Series Applicability Series Applicability Series
Entire H8S Series Yes H8S/2655 Yes H8S/2350
Yes H8S/2355 Yes H8S/2357 Yes H8S/2345
Yes H8S/2245 H8S/2148 H8S/2144
H8S/2138 H8S/2134 H8S/2128
H8S/2124 — — — —